234 abstracts: physics and chemistry 



ascribed to the surrounding topography which favors the drainage of 

 cold air down the mountain sides and its accumulation on the valley 

 floor, since there is no easy means of escape. Nocturnal cooling is also 

 at a maximum in the clear dry air of Colorado and it seems to be accen- 

 tuated under certain types of pressure distribution which prevail over 

 Wyoming and Idaho during the cold season. A. J. H. 



PHYSICS. — Selective radiation from various substances III. W. W. 

 Coblentz. Bulletin Bureau of Standards, Reprint 156. 1911. 



The present paper is a continuation of previous work (Bur. Bull. 

 Standards, Reprints 97 and 131) on this subject. The selective emis- 

 sion and absorption of the acetylene flame is investigated spectro- 

 radiometrically; also the selective emission of the Welsbach mantle, and 

 of the same material formed into a solid rod which was heated to incan- 

 descence electrically. 



The conclusions arrived at from the results of the experiments and 

 from historical inquiry are that the selective emission can be explained 

 on a purely thermal basis without invoking the hypothetical andunproven 

 assumption of the presence of "luminescence" and of catalysis. 



w. w. c. 



PHYSICAL CHEMISTRY. — Radiometric investigation of water of crys- 

 tallization, infra-red absorption screens and standard spectral lines. 

 W. W. Coblentz. Bulletin Bureau of Standards, Reprint 168. 

 1911. Journal Franklin Institute, October. 1911. 

 This is a continuation of previous investigations of the condition of 

 water in minerals (Bull. Bur. Standards, Reprint 45). The infra-red 

 transmission of tremolite and of opal are examined in extenso; the latter 

 after various stages of de- and rehydration. The spectroradiometric 

 analysis shows no distinction between "water of crystallization," "ab- 

 sorbed water," and "water of solid solution;" all showing the absorption 

 bands of water in its free liquid state. Tremolite is supposed to contain 

 dissolved water but the radiometric test, although sufficiently sensitive 

 for the purpose, failed to detect it. A group of miscellaneous substances 

 is described including gelatin, in which the moisture appears to be pres- 

 ent as "water of constitution." W. W. C. 



